Siemens 3UG4 - Page 38

System overview
3.5 Overview of the functions
3UG4 / 3RR2 monitoring relays
38 Manual, 05/2016, NEB927043002000/RS-AC/004
Function
Monitoring relays
3UG45
3UG46
01
11
12
13
8
14
15
16
17
18
31
32
33
21
22
41
25
51
Speed monitoring
Monitoring for speed
overshoot
— — — — — — — — — — — — — — — — — ✓
Monitoring for speed
undershoot
— — — — — — — — — — — — — — — — — ✓
Rated control supply voltage
Self-powered, without
auxiliary voltage
— ✓ ✓ ✓ — ✓ ✓ ✓ ✓ ✓ — — ✓ — — ✓ — —
Externally powered, with
auxiliary voltage
✓ — — — ✓ — — — — — ✓ ✓ — ✓ ✓ — ✓ ✓
✓
: Function available
1p: Monitoring is 1
-phase
3p: Monitoring is 3
-phase
—
: Function not available
○: Function available with limitations
1)
Detection causes problems with regenerative power recovery.
2)
By monitoring the voltage thresholds.
True root mean square measurement (tRMS) / use with frequency converters:
The monitoring relays work with an electronic measuring method which calculates the actual
(effective) value of a measured value (tRMS), regardless of whether the measured variable's
waveform is purely sinusoidal or distorted.
The measured signal must only meet the following requirements:
● Periodic waveform (sinusoidal) within the specified frequency range
● Continuous zero crossings
As long as the line on the primary or the secondary side in the environment of a frequency
converter fulfills these requirements, the monitoring relays can also be operated upstream or
downstream of frequency converters. The required line quality can be ensured by using line
filters/sine-wave filters where applicable. Of course, the suitability of the relevant monitoring
relay for the monitored line frequencies must also be considered.